In the use of a so-called thrust distribution ar for dental prostheses, it is common practice to provide a tooth stump with a crown which has a generally semicylindrical or semicircular cross section support surface receivable in a complementary recess of the thrust distribution arm and an axially opening and laterally opening groove adjacent the supporting surface of the crown in which a complementary rib on the thrust distribution arm is axially shiftable. A clamping rib is axially shiftable in another groove on the other side of the surface.
The thrust distribution arm to be part of a dental prosthesis, for example, in a bridge between two tooth stumps.
For fixing the thrust distribution arm with its recess to the corresponding support surface of the crown on one of these tooth stumps, the prosthesis is placed over the crown and the ribs are slid into the respective grooves. An adhesive composition may be inserted or some other means used to lock the prosthesis in place. The drawback of such means is that it generally has projecting parts which transfer with subsequent removal of the prosthesis, can serve as locations for accumulation of food residues or the like so that scale or plaque formation can occur with consequent irritation of the gums. The earlier configurations of the rib and groove constructions also were not capable of preventing canting of the prosthesis so that often the prosthesis was not precisely positioned and could not be effectively used without damage to the prosthesis or damage to the support stumps or inconvenience of the user.
Similar drawbacks applied to connecting elements utilized for other dental prostheses. For example, it is desirable to provide between two tooth stumps of which are material or synthetic, e.g. formed by implants, a bar bridging the crowns and onto which a prosthesis in the form of a supercrown is mounted. The supercrown may form part of a much larger prosthesis. It is desirable to provide rib and groove connections between the crown along the respective bar. In this case as well, the prosthesis could have a rib fitting into an open groove of such a bar, the prosthesis having a channel which receives the bar so that the bar also serves to hold the prosthesis in proper orientation.